Anyone who's seen the purple traps hanging from trees in the area or along the highway may now also notice yellow tags tied with purple ribbons on some of Buffalo's ash trees.

They are a sign that emerald ash borers are here. Or, if the pests aren't here yet, they will be soon.

Re-Tree WNY and the City of Buffalo have started tagging ash trees to raise awareness of the damage the emerald ash borer can cause. Late last month, Paul Maurer, chairman of Re-Tree, and Shane F.M. Daley, tree care supervisor for Buffalo's Olmsted Parks Conservancy, tagged trees along Delaware Avenue from Gates Circle to Summer Street.

Maurer said the tagging started because this is the start of camping season and transporting firewood is one of the ways the beetles have spread.

"We wanted to raise awareness for EAB and the threat it poses to all our ash trees," Daley said, "so that people can plan accordingly to what they need to do to save their trees or plan on having them taken care of or taken down."

The emerald ash borer, a beetle indigenous to Asia, is destroying ash trees in Cheektowaga, Lancaster and Buffalo, among other communities. Experts say it definitely will be spreading -- meaning no community in the region is safe from the pest that was discovered in 2002 in southeastern Michigan.

The emerald ash borer was first found in New York State a couple of years ago in the Town of Randolph in Cattaraugus County, with the first appearance in Erie County coming last June in Buffalo's South Park.

The larvae of the borer feed on the ash tree's circulatory system, eventually causing the entire tree to die, typically within two to three years of the initial attack.

Many in the area remember the destruction caused by Dutch elm disease. But a publication from NorthWoods Stewardship Center -- a Vermont conservation organization -- notes that while that disease killed about 200 million elms, the emerald ash borer could kill all the 7.5 billion ash trees in North America.

Paul Fuhrmann, acting coordinator of the Western New York Partnership for Regional Invasive Species Management, said the NorthWoods Center figure has been widely circulated and hasn't been disputed.

Fuhrmann said ash trees make up 15 percent of the forest cover in Erie County and 30 percent in Niagara County. One of the hardest hit areas is along Rehm Road in Lancaster, he said.

"It's in pockets and it keeps showing up in pockets," Fuhrmann said, noting the beetles can travel a mile or two to lay their eggs in an ash tree.

One reason the infestation is so difficult to fight is that cities, towns and villages have to manage tree care and removal of dead and fallen tree stock, all of which can be expensive. Costly equipment is needed to chop infected ash trees into chips small enough to kill emerald ash borer larvae.

"It really comes down to money, and I don't know any municipality that has enough resources to deal with this problem," Fuhrmann said.

Another concern is what to do with the leftover bits after the infected trees have been chopped up, said David Paradowski, supervising forester for the state Department of Environmental Conservation Region 9.

Raising enough nonstinging parasitic wasps that feed on the borer has proved challenging. Some of the wasps were released in Randolph last summer, Paradowski said, but the program is expensive as the demand for the wasps is high and the supply is low.

Another problem is that signs of infestation are initially hard to detect.

"By the time you notice it, they've been there three or four years," he said.

The presence of small D-shaped holes on branches and tree trunks is one clue. But woodpeckers also can hint at infestation, as they leave white marking signs in upper branches of infected ash trees, Paradowski said.

There are also many infected trees on private property, but it's difficult for DEC officials to contact and work with those landowners. Forester Pat Marren, who is stationed in the DEC's Buffalo office, is trying anyway.

Thomas Herrera-Mishler, president and chief executive officer of the Olmsted Conservancy, doesn't need to be reminded. About nine years ago, the parks stopped planting ash trees because of the emerald ash borer, although the beetle wasn't yet in Buffalo.

The parks, which had 42,000 trees before Dutch elm disease hit, are now down to 15,000 trees -- 10 percent of which are ash trees.

Daley said the conservancy has the funds to treat 75 to 100 medium-large to large ash trees for the next 25 years, including trees in the arboretum in South Park.

Herrera-Mishler believes the emerald ash borer will be twice as damaging to the parks' trees as the October Surprise storm of 2006.

"It's a slow-moving catastrophe," he said, adding that he expects the emerald ash borer to continue spreading. "I don't want to be an alarmist, but eventually all of the ash trees in North America will be affected by this pest. It's just nature doing what nature does."

A woods walk planned for 10 a.m. Wednesday at Como Park in Lancaster will give residents an opportunity to learn about the emerald ash borer and other aspects of forest and tree management.